CVE-2017-5647 in MySQL Enterprise Monitor
Summary
by MITRE
A bug in the handling of the pipelined requests in Apache Tomcat 9.0.0.M1 to 9.0.0.M18, 8.5.0 to 8.5.12, 8.0.0.RC1 to 8.0.42, 7.0.0 to 7.0.76, and 6.0.0 to 6.0.52, when send file was used, results in the pipelined request being lost when send file processing of the previous request completed. This could result in responses appearing to be sent for the wrong request. For example, a user agent that sent requests A, B and C could see the correct response for request A, the response for request C for request B and no response for request C.
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Analysis
by VulDB Data Team • 01/04/2021
The vulnerability described in CVE-2017-5647 represents a critical race condition and request handling flaw within Apache Tomcat's HTTP request processing pipeline. This issue specifically affects multiple versions of the Tomcat web server, spanning from version 6.0.0 through 9.0.0.M18, creating a widespread impact across the Tomcat ecosystem. The vulnerability manifests when the server processes pipelined HTTP requests in conjunction with file sending operations, fundamentally compromising the integrity of request-response mapping within the HTTP protocol implementation.
The technical root cause of this vulnerability lies in the improper synchronization and state management during the processing of pipelined requests when file transfer operations are involved. When Tomcat encounters a request that triggers file sending functionality, the server's internal request handling mechanism fails to properly maintain the correlation between incoming requests and their corresponding responses. This occurs because the file sending process, which is typically an asynchronous operation, does not properly account for the pipeline order of subsequent requests that arrive while the previous file transfer is still in progress. The flaw creates a scenario where the response for request C gets mistakenly associated with request B, while request C itself receives no response at all, effectively causing request loss and response misattribution.
The operational impact of this vulnerability extends beyond simple request loss, creating potential security implications and service disruption scenarios. An attacker could exploit this vulnerability to manipulate the flow of HTTP communications, potentially leading to session confusion, authentication bypass attempts, or denial of service conditions where legitimate users experience incomplete responses. The vulnerability particularly affects applications that rely heavily on pipelined HTTP requests, which are common in modern web applications for performance optimization. From a security perspective, this issue can be categorized under CWE-362, which describes race conditions that can lead to improper access control or data corruption, and aligns with ATT&CK technique T1211 for establishing persistence through request manipulation.
Mitigation strategies for this vulnerability require immediate patching of affected Tomcat versions to the latest stable releases that contain the fix for this race condition. Organizations should prioritize updating their Tomcat installations to versions that address this specific issue, as the vulnerability affects multiple major release lines and could remain undetected for extended periods. Additionally, system administrators should implement monitoring solutions to detect anomalous request-response patterns that might indicate exploitation attempts. The fix implemented by Apache Tomcat developers involved enhancing the request processing queue management and ensuring proper synchronization between file sending operations and the pipelined request handling mechanism, preventing the loss of requests during asynchronous file transfer operations.